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Date: Tue, 15 Apr 2025 08:41:28 +0100
To: internals@lists.php.net
Subject: Re: [PHP-DEV] Closure::getCurrent() for recursion
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")

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On 15 April 2025 00:01:18 BST, Krinkle <krinkle@fastmail=2Ecom> wrote:

>Eg:
>=20
>$a =3D function ($a) {
>  $aFn =3D Closure::current(=2E=2E=2E);
>  $aFn(4) =3D=3D=3D Closure::current(4);
>};

I think there's some confusion on this thread; as I understand it, the pro=
posal is not for a magic function to *call* the current closure, but a way =
to get a *reference to it*=2E

So you don't need, or want, the FCC syntax here - that would create a clos=
ure which, whenever invoked, executes the static method "current" on class =
"Closure"=2E

What you want is to call the Closure::current (or getCurrent) method direc=
tly, which will give you the existing closure, known as $a in the outer sco=
pe=2E Once you have a reference to it, you can pass it around and execute i=
t wherever you want=2E

$aOutside =3D function (int $foo) use (&$aOutside) {
  // Points to the same object as if you used by-ref
  assert($aOutside =3D=3D=3D Closure::getCurrent());
  // Store it wherever you like=20
  $aInside =3D Closure::getCurrent();
  assert($aInside =3D=3D=3D $aOutside);
=20
  // Call it like you would any callable=20
  $aOutside(42);
  $aInside(42);
  Closure::getCurrent()(42); // note the two sets of parens

   // Capture it into another closure
   $bOutside =3D function() use ($aInside) {
      // Get a self-reference in that one too=20
      $bInside =3D Closure::getCurrent();
      // Do whatever you like with $aInside and $bInside
   };
};


Rowan Tommins
[IMSoP]
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<!DOCTYPE html><html><body><div dir=3D"auto">On 15 April 2025 00:01:18 BST,=
 Krinkle &lt;krinkle@fastmail=2Ecom&gt; wrote:<br><br>&gt;Eg:<br>&gt; <br>&=
gt;$a =3D function ($a) {<br>&gt;=C2=A0 $aFn =3D Closure::current(=2E=2E=2E=
);<br>&gt;=C2=A0 $aFn(4) =3D=3D=3D Closure::current(4);<br>&gt;};<br><br>I =
think there's some confusion on this thread; as I understand it, the propos=
al is not for a magic function to *call* the current closure, but a way to =
get a *reference to it*=2E<br><br>So you don't need, or want, the FCC synta=
x here - that would create a closure which, whenever invoked, executes the =
static method "current" on class "Closure"=2E<br><br>What you want is to ca=
ll the Closure::current (or getCurrent) method directly, which will give yo=
u the existing closure, known as $a in the outer scope=2E Once you have a r=
eference to it, you can pass it around and execute it wherever you want=2E<=
br><br>$aOutside =3D function (int $foo) use (&amp;$aOutside) {<br>=C2=A0 /=
/ Points to the same object as if you used by-ref<br>=C2=A0 assert($aOutsid=
e =3D=3D=3D Closure::getCurrent());<br>=C2=A0 // Store it wherever you like=
 <br>=C2=A0 $aInside =3D Closure::getCurrent();<br>=C2=A0 assert($aInside =
=3D=3D=3D $aOutside);<br> <br>=C2=A0 // Call it like you would any callable=
 <br>=C2=A0 $aOutside(42);<br>=C2=A0 $aInside(42);<br>=C2=A0 Closure::getCu=
rrent()(42); // note the two sets of parens<br><br>=C2=A0=C2=A0 // Capture =
it into another closure<br>=C2=A0=C2=A0 $bOutside =3D function() use ($aIns=
ide) {<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 // Get a self-reference in that on=
e too <br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 $bInside =3D Closure::getCurrent()=
;<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 // Do whatever you like with $aInside a=
nd $bInside<br>=C2=A0=C2=A0 };<br>};<br><br></div><div dir=3D"auto">Rowan T=
ommins<br>[IMSoP]</div></body></html>
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